EP1628812A1

EP1628812A1 - Device for preparation of plastic materials for recycling purposes

Info

Publication number: EP1628812A1
Application number: EP04732068A
Authority: EP
Inventors: Helmut Bacher; Helmuth Schulz; Georg Wendelin
Original assignee: Individual
Current assignee: EREMA Engineering Recycling Maschinen und Anlagen GesmbH
Priority date: 2003-06-05
Filing date: 2004-05-11
Publication date: 2006-03-01
Anticipated expiration: 2024-05-11
Also published as: JP2006526519A; KR100744225B1; KR20060015331A; WO2004108379A1; BRPI0410943B1; ES2311820T3; DE502004008033D1; BRPI0410943A; PL1628812T3; DK1628812T3; ATA8872003A; CA2524331C; CA2524331A1; AT413512B; EP1628812B1; AU2004245126B2; CN100430197C; RU2310561C2; ATE407782T1; US7309224B2

Abstract

The invention relates to a device for preparation of plastic materials for recycling purposes, comprising a container (1) with an upper inlet opening (10) for the material. At least one tool (14) circulates around the vertical container axis in the container. Said tool leads the treated material towards an outlet opening (17) arranged in the bottom of the container (1) to which the housing (19) of at least one screw (21, 22) is connected. Each lateral wall (28) of the inlet opening (18), around which the tool (14) runs, defines a projection (36) extending continuously against the screw axis. Said projection (36) extends over a part of the circumference of the screw thread (30), such that the screw side edge of said projection (36) forms an uninterrupted cutting edge (39), cooperating with the screw threads (30).

Description

Device for processing plastic material for recycling purposes.

The invention relates to a device for the preparation of plastic material for recycling purposes, in particular thermoplastic material, with a container into which the material to be processed is introduced from above through a Einbringeöffnung, and arranged with at least one disposed in the container to the vertical axis of the Container circulating mixing and / or crushing tool, wherein the material treated by this tool is directed into a downwardly disposed in the container Ausbringeöffnung with which the feed opening of a connected to the container, preferably tangentially connected housing at least one screw in fluid communication, and wherein Side wall of the intake opening, where the tool runs, seen in section, a continuous against the axis of the housing of the screw extending extension of the intake opening edges. Such devices are known, for. B. AT 407 972 B. They usually have a

Extruder screw, which feeds the material funded by her directly downstream processing, usually a Granuliereinrichtung. The worm can also be a pure screw conveyor, which supplies the material to a downstream processing stage, for. B. a repeated processing by means of rotating tools, only from this processing stage, the material is fed to a plasticizing or agglomerating. The known devices operate satisfactorily in principle, but often have difficulties with respect to the feeding of the device connected to the discharge opening, in particular when this device is a plasticizing or agglomerating device. The aim is as uniform as possible indentation on the screw and thus the most uniform discharge of this device, which is particularly important when connected to an extruder a molding line, in which it matters that the material to be molded is fed as evenly as possible. The difficulties mentioned are due, among other things, to the fact that the material to be processed is generally very different, both in terms of the chemical composition of the material and in terms of its external nature (degree of soiling, particle size, particle shape, etc.).

The invention has for its object to overcome these difficulties and to improve a device of the type described so that the most uniform collection of the material to be processed in the intake opening of the screw housing is achieved, which is connected to the Ausbringeöffnung, so a uniform output at the discharge end of the screw, in particular a plasticizing or agglomeration is achieved. The invention solves this problem in that the extension, viewed in the direction of the axis of the housing of the screw, extends over a part of the circumference of the screw flights of the adjacent screw, preferably into the region of the screw axis, so that the screw-side edge of this extension cooperates with these screw flights uninterrupted shearing edge forms. This results in a constant intake of the material to be processed in the intake opening of the screw, even if the material is warm in the container. It can be assumed that this improved mode of action is due to the comparatively long shearing edge formed by the helical edge of the extension. Another significant advantage of the construction according to the invention is that the previously in the catchment area mostly necessary cooled Nutenbüchse, which is subject to heavy wear, is eliminated. This not only brings a cost saving, but also the advantage of a lower starting torque for the drive motor.

According to a particularly favorable development of the invention, the side wall surrounding the extension of the intake opening with the screw axis encloses an angle of 20 ° to 80 °, preferably 30 to 55 °. Likewise, it has proved by experiments to be particularly favorable for the aforementioned intake behavior, if the following formula applies to the intake opening of the housing of the screw:

h> k 0.6 d and

L ≥ k 0.6 d,

where h is the effective height of the intake opening measured in mm in the axial direction of the container,

L is the effective length of the intake opening measured in the circumferential direction of the container in mm, d is the outer diameter of the screws in mm and k is the number of screws, k preferably being equal to 1 or 2. Furthermore, it is favorable if the bottom of the intake opening of the screws in

Direction to the tank drops off.

The invention offers both advantages in constructions in which only a single screw is arranged in the housing connected to the discharge opening of the container, as well as in constructions in which two screws are mounted in this housing. This screw or these screws may be plasticizing or Agglomerierschnecken, but also pure transport screws. Up to now, the concerns of relatively high costs have been considered in twin-screw designs, but the experience of the applicants has shown that the complicated ones Measures that were necessary in single-screw constructions to achieve a reasonably uniform intake behavior approach the costs of a twin-screw design. In addition, in comparison to single-screw designs, the screws and their cylinders can be constructed much shorter by twin-screw designs and, with the same screw diameter, achieve about 1.5 to 2 times the output (eg when processing polyethylene).

However, Applicants' experiments have shown that it is advantageous in twin-screw constructions to maintain the advantages of pull-in behavior when the diameter D of the container to the diameter d of each of the two screws is as follows:

wherein

D is the inner diameter of the circular cylindrical container in mm or

Inner diameter of a converted to the same capacity fictitious circular cylindrical container of the same effective height, d the screw diameter in mm and K is a constant which is greater than or equal to 50, preferably greater than 100.

For non-cylindrical containers or non-constant screw diameter is to be converted, which will be discussed in more detail later.

Such twin screw designs make it possible compared to

Single screw designs to reduce the screw length shorter, shortened by about half, so that at the same output of the device a much reduced

Space requirement results. In the gusset area of the two snails are better

Plasticizing properties, since there the material is processed by shearing and kneading particularly intense. It has also been found that such a construction is less sensitive to the processing of mutually different types of plastic in terms of the screw geometry, so that the device is universally applicable.

Furthermore, it has been found within the scope of the invention that the smaller the surface touched by the material, the better the feeding of the device formed by the two screws and their housing, in particular if this is formed by a plasticizing or agglomerating device, which is present for the material to be processed between the container and the screws. According to one embodiment of the invention, therefore, the construction is such that when two screws in the housing the

Screws as close as possible to the container side edge of the intake. The

Housing is the plasticizing or agglomerating device formed by the screw Therefore, directly connected to the Ausbringeöffnung of the container, so that the intake opening of the housing of the plasticizing or agglomerating device of the discharge opening of the container is immediately adjacent or coincides with it. For this purpose, it is expedient if the housing of the two screws is connected as tangentially as possible to the circumference of the container, although in principle deviating arrangements are possible, for example, a radial arrangement.

The most favorable arrangement in the context of the invention results when the cross sections of the two screws in the housing of the plasticizing or agglomerating in the region of the feed opening are vertically or obliquely one above the other. This vertical arrangement gives the smallest surface which the material to be processed, which may sometimes be sticky, has to overcome from the container to the two screws. This is important in order to avoid sticking of the material to these surface sections. Is deviated from the vertical arrangement, e.g. with an oblique arrangement of the two screw cross-sections or even with a side-by-side arrangement, then it is usually necessary to arrange cooling channels in the housing of the plasticizing or agglomeration device in the region of the intake opening, in order to stick the processed material to these surface sections and thereby cause overheating of the latter to prevent jammed material.

The gears of the two screws can mesh with each other at least in the region of the intake opening. This has the advantage of a self-cleaning of the flights, which is especially important in the catchment area. Although the same screw diameters of the two screws are convenient, this is not essential and the two screws may also have different lengths, e.g. when one worm acts as a feeder screw for the other worm.

Further features and advantages of the invention will become apparent from the description of embodiments of the subject invention, which are shown schematically in the drawing. Fig. 1 shows a vertical section through a first embodiment, as seen along the section line I - 1 of Fig. 2, which shows a section along the line II - II of Fig. 1. Fig. 3 shows an embodiment in horizontal section with two adjacent screws of the same length. Fig. 4 shows a variant of FIG. 3, in which the two screws have different lengths. Fig. 5 shows in an arrangement with only one screw the formation of the intake opening. Fig. 6 shows the formation of the intake opening in an arrangement with two screws and Fig. 7 shows the formation of the intake opening of Fig. 5 in horizontal section. Figs. 8 to 14 show, each in vertical section, different Possibilities for the arrangement of the screws in twin-screw constructions. Fig. 15 shows in horizontal section an arrangement with a conical twin-screw extruder.

In the apparatus of FIGS. 1, 2, and 6 is a Zerreißer-extruder combination with twin screw, which has a container 1 with a vertical axis 2 and circular cross-section, the side wall 3 is substantially cylindrical. In the container 1 runs around the axis 2, a support disk 4 in the direction of arrow 8 (FIG. 2), which sits on a shaft 5, which passes through the bottom 6 of the container 1 sealed and rotatably supported in the bottom 6 in bearings 7. The shaft 5 is driven by a motor 9 for rotation.

The container 1 has at the top a Einbringeöffnung 10 for the material to be processed, expediently in a funnel-shaped top wall 11. If the material is to be processed under vacuum, an evacuation device is connected to the container 1, and the Einbringeöffnung 10 is expediently also evacuated Lock provided. To the introduction opening 10, the material to be processed is conveyed by a feeder 12, e.g. a conveyor belt, fed and thrown in the direction of arrow 13 in the opening 10.

The arranged in the region of the bottom 6 carrier plate 4 carries a plurality of tools 14, which act on the introduced into the container 1 material, usually thermoplastic recycled goods, at least mixing, usually also crushing and drying. In the latter case, the tools 14 are formed as blades with cutting. The material thrown off by the tools 14 from the carrier disk 4 rises on the side wall 3 of the container 1 in the form of a mixed stream 15 and, after reaching a culmination point 16, falls back into the area of the container axis 2. In this way, the processed material is well mixed or crushed and dried and discharged after reaching a sufficient residence time in the container 1 from this through a Ausbringeöffnung 17 (Fig. 2), which in the illustrated embodiment with the intake opening 18 of the housing 19 of a twin-screw arrangement a plasticizing or agglomerating device 20, eg an extruder collapses, but at least is in fluid communication therewith. The device 20 has two screws 21, 22 arranged in the housing 19, which are driven in synchronism by a motor 23 in the same direction of rotation so that their worm threads can mesh with one another. A suitable drive arrangement suitable for this purpose is shown in FIGS. 3 and 4. The motor 23 drives a sun gear 24, which is mounted in a transmission housing 25 and two planetary gears 26, 27 drives, which are rotationally connected to the shafts of the two screws 21, 22.

To achieve a double compared to a single screw extruder Output quantity has proved to be advantageous if the container dimensions of the relationship satisfy the following empirically determined rule of thumb:

where D is the inner diameter of the container 1 in mm, d is the worm gear outer diameter of the two screws 21, 22 in mm and K is a constant which is at least 50, but preferably at least 100. This formula applies to a circular cylindrical container. If this container is not circular cylindrical or non-cylindrical, such as conical, D is to be converted to the inside diameter of a fictitious circular-cylindrical container of the same capacity, i. same effective height. As effective height H here is any distance in which the culmination point 16 of the Mischtrombe 15 is above the upper edge of the support plate 4, assuming reasonable operating conditions. For different screw diameters, in the aforementioned formula for d, the mean value of the screw diameters is to be taken. If the screw diameter is not constant over the screw length (e.g., conical screws), then the mean screw diameter should be used.

As mentioned, but also the design and design of the intake opening 18 of the screw housing 19 is important. In this intake opening 18, which is at least partially at the height of the circulating in the container 1 tools 14, the mixed in the container 1, optionally crushed, and thus heated and optionally dried plastic material is thrown from the tools 14. This can be assisted by the fact that the edges of the tools 14, which are seen in the direction of arrow 8, are angled or bent counter to the direction of movement so that a spatula-like indentation of the material into the intake opening 18 results during the rotation of the tools 14. Experiments have shown that particularly favorable conditions are present if the following dimensions apply to the intake opening 18:

h> k 0.6 d and

L ≥ k 0.6 d,

where h is the effective height of the intake opening 18 measured in mm in the axial direction of the container 1, in mm,

L measured in the circumferential direction of the container 1 effective length of

Inlet opening 18 in mm, d is the outer diameter of the screw threads in mm, and k is the number of screws, where k is preferably 1 or 2.

As an effective length or effective height of the intake opening 18 in this case is effective in relation to the direction of passage of the material from the container 1 in the housing 9 clear cross-section. For non-constant screw diameters d is to be converted as mentioned above.

Furthermore, tests have shown that the introduced into the intake port 18 material sometimes tends to stow in the region of that edge of the intake opening 18, on which the tools 14 run, in Fig. 2 so the left edge of the intake opening 18. To such It has proven to be useful to avoid that side wall 28 of the intake opening 18, on which the mentioned tools 14 run off (this is the side wall 28 lying on the right in FIGS. 3 and 4), so obliquely with respect to the longitudinal axis 29 to arrange the worm housing 19 that, viewed in the direction of entry of the plastic material, a continuously extending in the direction of the screw axis 36 of the intake opening 18 forms. The angle α (FIG. 7), which encloses this side wall 28 with the longitudinal axis 29 of the screw housing 19, is in any case less than 90 °, namely 20 to 80 °, preferably 30 to 55 °. The side wall 28 in this case extends to at least the circumference of the screw flights 30 of the adjacent screw 21 or 22, preferably into the region of the axis of this screw. This longitudinal axis of the screw falls in a vertical arrangement of the two screws 21, 22, seen in plan view, with the axis 29 of the screw housing 9 together (Fig. 2). In single-screw constructions (FIGS. 5, 7), the side wall 28 extends at least over a part of the circumference of the screw flights 13 of the screw, preferably into the region of the screw axis. In all cases, forms the edge of this side wall 28, in particular its end, a cooperating with the screw flights 30 shear edge 39 (Fig. 1, 5, 6), which, since no Nutenbüchse is arranged in the circumferential direction of the screw 21, 22 continuously, ie without interruption, runs.

In the embodiment of FIGS. 1, 2 and 7, the two screws 21, 22 are arranged vertically one above the other, and the Scheckenachsen are horizontal. Both are not absolutely necessary, although these arrangements are the cheapest. If it is necessary to deviate from this, as can be seen in FIGS. 3 and 4, the two screws 21, 22 lie horizontally next to each other. In the embodiment of Fig. 3, both worms 21, 22 are of equal length and driven in the same direction of rotation, their worm threads 30 can mesh with each other. Both screws 21, 22 thus jointly convey into an extruder head 31 connected to the screw housing 19.

The arrangement according to FIG. 4 differs from that according to FIG. 3 in that the two screws 21, 22 have different lengths, that is, the screw 21 adjacent to the container 1 is shorter than the other screw 22. The screw 21 Therefore assumes the ejected from the container 1 through the Ausbringeöffnung 17 in the intake opening 18 of the screw housing 19 material, this intake behavior is improved by the aforementioned design of the container 1 and the intake opening 18 and by the design of the side wall 28 thereof. The screw 21 passes in the course of its conveying path, the material taken over by her to the other screw 22, which supplies the material to the connected extruder head 31. This arrangement has in addition to the advantage of a uniform intake nor the benefits of a cheaper discharge housing 37 and a cheaper inlet piece to the extruder head 31. The detailed design of the intake opening 18 for constructions according to FIGS. 3 and 4 is shown in Fig. 5.

From Figs. 5, 6 and 7 it can be seen that even at that edge of the intake opening 18, on which the tools 14 run, d.i. 5, 6 and 7, the right edge, a chamfer 32 is provided to improve the intake behavior. Furthermore, the bottom 33 of the intake opening 18 is inclined in the direction of the container 1, so that the wall of the intake opening formed by it drops off the worm 22 in the direction of the container 1.

As already mentioned, the two screws 21, 22 can in principle assume any position relative to each other. Different arrangements are shown in Figs. 8 to 14. The position shown in Fig. 11 of the two screws 21, 22 vertically above each other is the most favorable arrangement, because then the risk of sticking of plastic particles on the surface of the catchment area of the screw housing is not given, unlike other position of the screw 21, 22nd Although deviating from the arrangement of FIG. 11 arrangements are also useful in principle, however, in such arrangements, the aforementioned sticking of eg sticky plastic particles and the consequent growth of the feeding opening is possible. This can lead to overheating of these material particles. In order to avoid this, it is advisable to arrange cooling channels 34 in that region of the section of the housing 19 which is bounded by the intake opening 18, where cavities 35 are located after the intake opening, in the case of arrangements of the screws 21, 22 deviating from FIG. which can lead to the mentioned sticking and the consequent excessively long residence times of the processed material particles. The larger these cavities 35 and the more they extend in the housing 19 in the direction of the container 1, the more cooling channels 34 are expediently provided. Although the formation of the two screws 21, 22 with the same and constant gearing diameter d (FIG. 7) is the most cost-effective, this is not absolutely necessary. Namely, Fig. 15 shows an embodiment with two screws 21, 22, which are both conical and together a Form twin-screw extruder, which promotes to an extruder head 31. The two

Screws 21, 22 are in this case driven in opposite directions via intermeshing gears 38 by a common motor 23. Their worm threads 30 can mesh with each other, so that in this embodiment, a self-cleaning in the catchment area is achieved.

Although the horizontal arrangement of the one or two screws having housing 19 is the cheapest, it is in principle possible to connect this housing with inclined longitudinal axis of the container 1, possibly even vertically.

Although only two screws are shown in each case in the embodiments described above, it is also theoretically possible to use designs with three or more screws in an analogous construction, for which constructions the aforementioned formulas also apply. Such provided with three or more snails

Constructions are not essential for economic reasons.

Claims

Patent claim:

1. An apparatus for the preparation of plastic material for recycling purposes, in particular thermoplastic material, with a container (1), in which the material to be processed is introduced from above through a Einbringeöffnung (10), and arranged with at least one in the container (1) to the vertical axis (2) of the container (1) circulating mixing and / or crushing tool (14), wherein the material of this tool (14) treated material in a container (1) arranged below Ausbringeöffnung (17) is passed with the the feed opening (18) of a housing (19) of at least one screw (21) connected to the container (1), preferably tangentially, is in fluid communication, and wherein that side wall (28) of the feed opening (18) on which the tool (14 ) runs, seen in section, a against the axis (29) of the housing (19) of the screw (21) continuously extending extension (36) of the intake opening (18) edges, characterized gekennzeich net, that this extension (36) moves towards the axis (29) of the

Housing (19) of the screw (21, 22), over a portion of the circumference of the screw threads (30) of the adjacent screw (21, 22) extends, preferably into the region of the screw axis, so that the screw-side edge of this extension (36) a cooperating with these flights (30) uninterrupted shear edge (39) forms.

2. Apparatus according to claim 1, characterized in that the extension (36) delimiting side wall (28) of the intake opening (18) with the screw axis forms an angle between 20 and 80 °, preferably between 30 and 55 °.

3. Apparatus according to claim 1 or 2, characterized in that for the intake opening (18) of the housing (19) of the screw (s) (21, 22) the following formulas apply:

h> k 0.6 d and

L ≥ k 0.6 d,

in which: h is the effective height of the intake opening (18) measured in mm in the axial direction of the container (1),

L measured in the circumferential direction of the container (1) effective length of

Feed opening (18) in mm, d, the outer diameter of the screw (21) and the screws (21, 22) in mm and k is the number of screws, k being preferably 1 or 2.

4. Device according to one of claims 1 to 3, characterized in that the bottom (33) of the intake opening (18) of the screw (21, 22) in the direction of the container (1) drops.

5. Device according to one of claims 1 to 4, characterized in that in two screws (21, 22) in the housing (19), the screws (21, 22) as close as possible to the container-side edge of the intake opening (18).

6. Device according to one of claims 1 to 5, characterized in that in two screws (21, 22) in which the screws (21, 22) adjacent wall portion of the housing (19) cooling channels (34) are provided.

7. Device according to one of claims 1 to 6, characterized in that in two screws (21, 22) of the diameter (D) of the container (1) to the diameter (d) of each of the two screws in the following relationship:

D = 10K

wherein

D is the inner diameter of the circular cylindrical container (1) in mm or

Inner diameter of a converted to the same volume volume fictitious circular cylindrical container of the same effective height, d is the screw diameter in mm and

K is a constant which is greater than or equal to 50, preferably greater than 100.

8. Device according to one of claims 1 to 7, characterized in that in two screws (21, 22), the cross sections of the two screws (21, 22) in the region of the intake opening (18) are vertically or obliquely one above the other.

9. Device according to one of claims 1 to 8, characterized in that in two screws (21, 22) the worm threads (30) of the two screws (21, 22) at least in the region of the intake opening (18) mesh with each other.